Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a device for use in electro-
magnetic displays or indicators.
The type of device with which this invention is concerned
has disks pivotally mounted in approximately their median plane,
contrastingly colored on opposite sides and carrying a permanent
magnet having an axis with a component transverse to the pivot
axis. A selectably reversible field forming means external to the
disk controls the orientation of the disk by the influence of the
field on the permanent magnet and causes it to display one or the
other of its contrasting faces in the viewing direction.
Such disks are frequently arranged in columns and, in
such columns, are frequently arranged in a single frame. To obtain
greater visibility for the disks of the display, it is sometimes
desireable to make the disk oval instead of circular with its long
dimension corresponding generally to the longitudinal direction of
the column of the array. If the pivot axis is then directed in the
column direction so that the pivot axes of all the disks in a
column are coaxial, then the disk spindles and the spindle wells for
the disks require space between adjacent disks in the column and
such space detracts from the appearance of the display since it
decreases the area of the display which may be reversed in appearance.
Accordingly, in one aspect of the invention, the spindle
wells for adjacent disks in a column are provided in overlapping
arrangement so that the frame mount between two adjacent disks
contains overlapping wells opening in opposite directions for the
pivot spindles of the disks on each side of the frame mount. The
axes of the disks in a column, although still substantially parallel
are no longer coaxial, the axes being stepped from each other by
roughly the spacing of the overlapping spindle wells. There .s
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therefore a small angle between the axis of the disks and the
plane of the display. In this way the disks may be brought closer
together in the column direction reducing the unused (by contrasting
surfaces) area of the display.
In preferred applications of the arrangement discussed in
the previous paragraph, the row of disks is arranged vertically.
In such orientation, the display usually being viewed at an angle
below the normal to the sign, the disks are, in such event, oriented
so that the normal to the disks slopes downwardly at an angle to
improve the appearance to the normally placed viewer.
It may be suitable here to discuss the criteria for the
change of angle of the axis to the longitudinal row direction. The
upper limit for such angle will be set by the requirement to provide
a suitable viewing angle. It is difficult to visualize situations
where this angle would be greater than 10 and for most applications
5 will be the upper limit. In the preferred method of making the
device the spindle wells will be formed in the molded plastic frame.
The minimum angle between the disk axes and the plane of the display
will be controlled by the minimum thickness dimension between the
two bearing wells which can suitably be molded in plastic. This sets
th~ angle of the spindles to the row axis at about 3 and it will be
difficult to obtain the required separating wall thickness with the
angle appreciably smaller. However, it must be realized that the 3
and 10 cannot be regarded as absolute limitssince the angle between
the disk axis and the column direction will change with each disk size.
In many applications including, in particular, bus destin-
ation signs, there is ample room for the height of the display but
very limited available width. Accordingly, in order to increase the
visibility of such signs, it is desireable to increase the height of
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the display without altering the width. It will then be desireable
to increase the disk in the corresponding dimension. With the
nearly vertical slightly sloping disk axes, the disks are then made
oval shaped and symmetrical about the disk axis (with the exception
of a notch as hereafter described) and the long dimension of the
oval along the disk axis. The result is an array extended in the
height dimension.
In another aspect of the invention, the magnetic field
forming members, exterior to the disk, have magnetic cores energized
by windings, with the forward core ends just rearward of the plane
of the disk in each orientation of the latter. One edge of the
disk is therefore notched to allow the disk to pass the core end and
any associated support in rotating from one orientation to the
opposite orientation. The permanent magnet is preferably contained
in the plane of the disc. The magnetidefining a magnetic axis trans-
verse to the pivot axis, is displaced transversely to the pivot
axis, away from the notch, so that the outer pole of the magnet is
adjacent one of the core ends in each orientation of the disc~ (With
such preferred assymetric disposition of the magnet the inner pole
of the magnet has almost no effect on the operation). MeanS are
provided adjacent each pole piece for stopping the rotation of the
disc inward of the edge to avoid irregularities which sometimes
occur on such edge. The spacing is also provided to avoid magnetic
switching of the core polarity due to the close proximity to the
permanent magnet.
In another aspect of the invention, the magnetic field
forming members, exterior to the disk, have magnetic cores energized
by windings, with the forward ends of the cores just rearward of the
plane of the disk in each orientation of the latter. One edge of the
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disk is therefore notched to allow the disk to pass the core and
and any associated support in rotating from one orientation to
the opposite. The permanent magnet is preferably contained in the
plane of the disk. The magnet defining a magnetic axis transverse
to the pivot axis, is displaced transversely to the pivot axis,
away from the notch. The outer edge of the permanent magnet is
located within a truncated 45 cone whose axis is perpendicular to
the rest position of the disk and which cone enlarges from the core
end toward the disk. This location of the outer end of the per-
manent magnet ensures good starting torque for the disk when thecore is reversed to reverse the orientation. It will be noted that
the de~ign is such that the above defined geometrical relationship
will be true for whichever core end is located near the outer end
of the assymetrically disposed magnet. The good starting torque
avoids the necessity of an extra bias magnet of the type required in
the design shown in U.S. Patent 3,518,664 dated June 30, 1970 to
M.K. Taylor.
It should be clearly noted that in connection with the
aspect of the invention just mentioned and with that aspect where
the contact stop for the disk is inboard of its edge, the advantages
apply to single disk indicators (often known as status indicators)
and in these aspects, therefore the invention is not limited to use
with a plurality of disks in a column. It should also be noted that
the last mentioned two aspects apply to a disk whose pivotal axis
is not slanted.
In the preferred form of the invention the disk is of the
type disclosed in U.S. Patents 3,871,945 dated March 18, 1975 and
(its divisional) 3,953,274 dated April 27, 1976, both naming as
~24014~3
inventors Winrow et al. The disk is thus made of 3 layerslaminated
together, the middle layer is apertured in the shape of and to
receive a magnet of approximately the thickness of such middle
layers. It will be obvious that this method of construction allows
the preferred assymetric disposition of the magnet to the extent
desired without inconvenience since the middle layer is merely
punched at the selected location and the magnet inserted during the
construction of the disk. In the patented construction, moreover,
the middle layer is shaped to provide projecting spindles which form
the mounting spindles of the disk. (It should be noted that each
of the outer layers is usually two sub-layers. The outer layer
corresponding to the dark side is usually a sub-layer of mylar with a
sub-layer of dark tape thereover to produce the dark outer surface
on the ultimate disk. The opposite side of the disk will customarily
have a s~ -~er of vinyl colored to the bright color required, and
sub-layer being an outer transparent protective casing. In general
however the disk is assembled as a three layer lamination, the mylor-
dark covered sub-layers being applied as a single layer to one side
of the central layer and the vinyl-protective covering sub-layers
being applied as a single layer to the other side of the central layer.
Although the inventive aspects defined herein are suited
to the previously patented laminar disk, it must be emphasized that
in the broad aspects of the invention, including the aspect of
tilting the disk axes relative to the row axes and the aspect of
stopping the disk with a contact inward of the disk edge are not
limited to use of the patented disk.
In drawings which illustrate the preferred embodiment of
the invention :
Figure 1 is a perspective and partially exploded view of a
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part of a row of disks in accord with the invention,
Figure 2 is a sectional view taken along the lines 2-2
of Figure 1,
Figure 3 is a rear view of the row of disks of Figure l;
Figure 4 is a vertical section in a plane parallel to the
viewing direction, and
Figure 5 is a partial cross-section of the device showing
these elements which indicate the relationship of the permanent
magnet outer edge to the core end.
In the drawings :
Figure 1 ~hows the frame 10 running longitudinally along
direction L and such frame at each end, n the preferred embodiment,
is provided with means defining mounting grooves 12 which allow a
plurality of frames 10 to be mounted side by side on transverse
coupling members received in grooves 12, to form an array. The
transverse direction is indicated by lines T-T. An analogous method
of mounting longitudinally extending display frames is shown in
U.S. Patent 3,942,274 dated March 9, 1976 to Winrow although, in that
patent, the transverse grooves are forwardly directed.
It will be understood that the directions L, T define a
display plane in such a device and that the usual viewing direction
V is tilted downwardly from the perpendicular P to such plane.
In the drawings the frame defines transverse walls 14 at
each end and located between adjacent ones of the longitudinally
disposed disks 16. Each transverse wall 14 is provided with a
forwardly directed mounting projection 18. Adjacent mounting pro-
jections 18 are provided with facing wells 20 to received the disk 16
spindles 22. As best shown in Figure 4 the facing wells 20 of
adjacent projections 18 are displaced in the forward direction to tilt
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the disk pivot axis to the vertical a sufficient degree so that the
wells 20 on opposite sides of a projection 18 overlap in a vertical
direction. The wells, as previously explained will normally be
displaced to produce an angle A of the spindle axes to the vertical
of about 3.
The disk 14, preferably constructed as defined in Patents
3,871,945 and 3,953,274, previously referred to, comprises a
lamination of three layers. Each of the two outer layers 24 and
26 are usually made from two sub-layers. The light side layer 24
0 i9 usually an inner sub-layer of vinyl colored for the light color
designed with an outer transparent protective sub-layer. The dark
side layer 26 is usually a inner sub-layer of mylar with an outer
sub-layer of tape to provide the dark color. The middle layer 28 is
preferably of ~ylar to correspond to that of the magnet 30. The
mylar layer has sufficient strength that it supports the extending
stub shafts 22 which are formed as an integral part of the middle
layer. The stub shafts 22 may be inserted in wells 20 by slightly
bending the resilient (due to the resiliency of the mylar) disk to
achieve insertion.
As best shown in Figure 1 the middle layer 28 is provided
with a slot shaped to receive the permanent magnet 30 which is
preferably made of the copper-nickel-iron alloy cunife magnetized
to provide a magnetic axis in the median plane of the disk trans-
verse to the pivot axis defined by spindles 20. The poles '~' and
'S' of the permanent magnet are shown in the drawings~
The middle layer 28 of the disk i9 recessed and the magnet
is located so that it is displaced to be all on one side of the
pivotal axis at about the midway point hetween the stubs 22. On the
edge opposite the assymetric displacement direction of the magnet is
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provided a notch 36 for a purpose to be hereafter discussed.
The disk is preferably made longer than it is wide to take
advanta~e of the fact that in many applications, such as bus signs,
there is more available space in the vertical than in the horizontal
dimension so that the height of the disks is increased to give
greater visibility.
The shape of the disk is a compromise. An oval disk
terminating in semicircles at each end would give a better visual
impression than a rectangle for disks collectively defining a
diagonal. However, the oval disk does not use as much of the
available display area as desired. Therefore, the compromise shape
with curved end and corners as shown is used.
As noted the use of overlapping wells and angled spindles
allows more complete use of the available display space in a row
by allowing the disks to be placed more closely together.
Actuation for the disk to turn it to one or the other orient-
ation is provided by a reversible magnetic field forming means,
exterior to the disk and acting on the permanent magnet 30. The
exterior field forming means in the preferred embodiment is provided
by a pair of core members 38 of high carbon, steel, having a relatively
high remanence. The core members 38 are fixed in position on each
side of the frame and extend through bores therein to project rear-
wardly of the frame, as shown and forwardly to the vicinity of the
disk (and magnet) locus when the disk is displaying one or the other
of its contrasting sides in the viewing direction. The m~ded plastic
frame provides on each side inwardly facing abutments 40 each of which
partielly surrounds a core 38 adjacent the core forward end. As shown
in Figure 2 the forward end of each abutment 40 has a forwardly and
inwardly sloping surface 42 which is located forward of the forward
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end of core member 38 and shaped to contact the disk 16 inwardly
of its edge.
The contact is made inwardly of the disk 16 edge because
the construction of the disk sometimes leaves a small (not visible)
accretion of adhesive or tacky material at the edge. The inwardly
displaced contact does not contact such material and the risk of
the disk sticking is therefore reduced.
The surface 42 stops the disk at a limiting position which
is a location spaced from the core 38 end because it is preferred
to use high carbon steel for the pole pieces. This material, al-
though of relatively high remanence is of lower remanence than some
core materials (such as vicalloy) previously used in controlling
display disks. With the high carbon steel cores 38, therefore, care
must be taken that the spacing between the ends of cores 38 and the
permanent magnet 30 of the disk is such that the permanent magnet
cannot alter the magnetic polarization of the core 38 and to cause
latching of the disk. Accordingly, surface 42 is shaped to achieve
the desired spacing which will be determined in accord with the cores
38 and magnet 30 used.
The disk opposite magnet 30 is provided with the notch 36
shaped to clear core 38 and abutment 40 during rotation of the disk.
Cores 38 project rearwardly of the frame and mount energizing
windings 46 which magnetize the cores in the desired polarity. The
bridging member 48 of iron having soft magnetic qualities is attached
to the cores 38 rearwardly of windings 46 to complete the magnetic
circuit between the cores 38. Terminal posts 50 are mounted to
project rearwardly from the frame corresponding to each core 38 and
designed at their rearward end for connection to an electrical
circuit, not shown. The leads 52 to the windings 46 are preferably
-
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soldered to terminal posts 50 at the latter's rearward end. The
windings 46 are connected in series so that energization to the
paired terminal posts will magnetize the paired cores 38 so that
one core forward end is north and the other south. These
polarities are simultaneously reversed to rotate the disk.
With the disk axes sloped, as shown in Figure 4, the
assymetric arrangement of the disk, as shown in Figure 1, aids in
the operation of the disk. As noted, with any of the disks, a
notch is removed from one side and the magnet is di~placed toward
the other. The weight bias in favour of the magnet displacement
side together with the axial tilt assists the disk to start to turn
as soon as the core is reversed to release at from a limiting
position. This renders operation of the disk more certain.
As illustrated in Figure S the permanent magnet 30, in its
rest limiting position of Figure 2 has its outer edge 31(corres-
ponding to the N pole) within a 45 truncated core whose axis is
perpendicular to the disk rest position and which expands from the
core end in the direction of the disk. The location of the outer-
most edge 31 of the permanent magnet is indicated by the line E and
the boundaries of the cone, as they appear in Figure 5 are defined
as CR and CL respectively. It will be obvious that the outer edge 31
of the permanent magnet is well within this cone. The practical result
is that on reversal of the core magnetism the repulsive force from the
core on the magnet is more nearly perpendicular to the disk than
parallel, giving a good starting torque to the disk and avoiding the
necessity of providing an extra bias magnet. The cores 38 are of
course located so that the same effect occurs when the disk is in its
opposite limiting position to that shown in Figure 2, that is with
the ~ end of the permanent magnet to the left and the notch to the
--10--
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right. obviously the geometrical relationship will hold true
where as shown the cores 38 are symmetrically disposed with
respect to the pivotal axis.
As previously noted the feature of the invention just
described, and that relating to the stop for the disX inboard of
the disk apply to disks used singly as well as to a plurality of
disks in rows; and both features apply to disks whether or not
their pivotal axes are slanted.
In operation with the cores magnetized as indicated in
Figure 2 (by the dotted N and S) the disk would rotate (clockwise
in Figure 2) to, and remain in, the position there shown, corres-
ponding to the middle disk of Figure l. When windings 46 are
energized to reverse the polarities of the cores, the disk under
the control of permanent magnet 30 will rotate (counterclockwise
in Figure 2) to and remain in the position there shown, corresponding
to the middle disk of Figure l. When windings 46 are energized to
reverse the polarities of the cores, the disk under the control of
permanent magnet 30 will rotate (counterclockwise in Figure 2) until
the non-notched edge of the disk is resting on the left hand
surface 42. The disk will then remain in that position until the
cores are again switched.
In all aspects of the invention the polarity of the permanent
magnet may be reversed and the operations and advantages will be
the same, the positions of the disk being obtained by opposite mag-
netizations of the cores.
